Polymorphism and Crystal-Engineering

Polymorphism describes the ability of a chemical substance to form more than one crystalline state. These different crystalline states have distinct properties with respect to solubility, colour, or melting point. This phenomenon is known for inorganic and organic molecules. Polymorphism is especially interesting in cases of pigments and pharmaceuticals. X-ray powder diffraction is exceptionally suited to distinguish between different polymorphs. The high transmission of the X-rays even allows the investigation of formulated and packaged pharmaceutical tablets (in blisters) and can be used to detect counterfeits.